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Herpesvirus infection was diagnosed in two parrots that died suddenly in a pet shop. Gross lesions were confined to reddening of the small intestinal mucosa. Histological examination of tissues from one specimen revealed a hepatitis and splenitis accompanied by intranuclear inclusions. Cowdry type A inclusions were observed in tissue culture and within the nuclei of chick embryo hepatocytes. Virus particles with a morphological similarity to herpesviruses were identified in electron microscope studies. The condition was considered to represent a case of Pacheco's parrot disease.

The isolation of reoviruses from broiler breeder and layer replacement stock affected with tenosynovitis is recorded. Experimental inoculation of the reovirus isolates in Brown Leghorn chickens produced mild clinical and pathological changes. Virus isolations from the affected joints ceased 15 days after inoculation but continued until day 35 from the caecal tonsil. All inoculated birds developed precipitating antibodies which persisted for at least 46 days.

A survey was carried out on the causes of mortality in three broiler breeder flocks during the laying period from May 1976 to February 1977. Five hundred and forty-two birds were examined. The commonest causes of death in the females were reproductive disorders (24.9%), cellulitis or injury due to cannibalism (24.0%), kidney lesions (9.5%), liver haemorrhage (7.1%), Marek's disease (4.9%) and staphylococcal synovitis/tenosynovitis (4.1%). Mortality in the males was due mainly to staphylococcal synovitis/ tenosynovitis (33.8%) and acute heart failure (14.3%).

Beak, tongue and other oral lesions were observed in broiler breeding fowl reared under a regime of separate sex feeding. Seventy four per cent of the male birds examined at necropsy, at 60 weeks of age, had beak lesions. Severe beak lesions, in both male and female birds, resulted in pronounced beak deformities which made feeding difficult or impossible. Beak lesions occurred at a number of sites on maxillae and mandibles but the pathogenesis of all lesions, including those of the tongue and oral cavity, appeared to be similar.It is postulated that the primary event was either direct or indirect injury of the epidermis, followed by bacterial infection and tissue necrosis. Dermatitis may arise in a number of ways and certain husbandry systems may encourage beak trauma. Because pronounced beak deformities and concurrent osteomyelitis were the usual outcome of progressive lesions, special vigilance is required to identify and cull affected birds whose welfare is seen to be at risk.

An outbreak of mycotic encephalitis caused by a fungus resembling Dactylaria gallopava was encountered in two flocks of broilers that were placed on bark litter. The fungus was isolated from the brains and lungs of affected birds and also from the litter. The condition was reproduced experimentally.

Leg deformities were investigated in two flocks of male broilers. The most frequently encountered lesions were a progressive valgus deformity of the intertarsal joint, dyschondroplasia and an abnormal thickening of growth plates. No chondrodystrophy was observed. In one flock the peak incidence of leg deformities occurred between 3 and 7 weeks of age and 75% of all valgus abnormalities were diagnosed between 22 and 35 days of age (P < 0.001); 62% of broilers with leg abnormality in this flock had growth plate lesions in one or more bones compared to 40% in broilers without deformity (P < 0.001). Although a relationship is indicated between the presence of dyschondroplasia - particularly in the distal tibio-tarsus - and valgus deformity it was considered that dyschondroplasia would increase the likelihood of distortion without necessarily being a pre-requisite for the initial deformity. The terminology of the lesions is discussed.

Intranasal vaccination with the H120 strain of infectious bronchitis virus (IBV) produced serum neutralisation indices of three or more in nine out of 12 birds. This afforded complete protection against intravenous challenge with the nephritogenic H52 strain of IBV and prevented the multiplication of virus in the kidney.Passive immunisation with homologous convalescent serum protected the kidney but not the respiratory tract against similar challenge. The frequency of virus isolations from the kidney was reduced, the agar gel precipitin response lowered and the haemagglutination inhibition response abolished.

Egg transmission of Mycoplasma synoviae (Ms) was demonstrated in broiler breeder birds of over 40 weeks of age from a commercial flock that had been infected during rearing and in birds experimentally inoculated before onset of lay. Infection of growing birds with Ms did not prevent egg transmission in adult life.The embryonated eggs of experimentally infected hens were less susceptible to infection by inoculation than those of specific pathogen-free birds. Some chicks with maternal antibody were found to be infected at hatching and in these maternal antibody was not mycoplasmacidal. Indeed by protecting the embryo maternal antibody may have promoted hatching of infected chicks.

Ten-fold serial dilutions of the H52 vaccine strain of infectious bronchitis virus were inoculated intravenously into 3-week-old and 10-week-old chickens. The severity of the histological lesions in the kidney was graded and described. The younger birds were much more resistant to the nephritogenic effects of the virus. Although very small doses of virus caused nephritis, no marked dose-related response was demonstrated in either age group.